I don't think Xatu should be ranked higher than Espeon. Sure, it can be splashed more easily on most teams, but Espy makes full Baton Pass chains a pretty powerful force. It can also pass Calm Mind in mini-chains.
So yea, Espeon should be Rank B. Nothing can duplicate its role of passing Calm Mind while blocking hazards, and it makes an entire play-style (as degenerate as it is) viable.